3rd generation partnership project (3GPP) long-term evolution (LTE) is a technology for enabling high-speed packet communications. Many schemes have been proposed for the LTE objective including those that aim to reduce user and provider costs, improve service quality, and expand and improve coverage and system capacity. The 3GPP LTE requires reduced cost per bit, increased service availability, flexible use of a frequency band, a simple structure, an open interface, and adequate power consumption of a terminal as an upper-level requirement.
Generally, each radio access technology has defined specific classes of terminals in terms of radio capabilities. Generally, the aim to mandate certain essential functions/requirements can help to simplify the system definition as well as the realization options (e.g. mandating 20 MHz of downlink (DL) reception as well as 20 MHz uplink (UL) transmission bandwidth significantly reduced the 3GPP LTE system complexity). Especially, mandating certain terminal functions may be useful for the system design if a defined subset of parameter combinations are also supported by the systems, e.g. the eNB scheduler. However, there is also a risk that not all the defined features are deployed in the networks at the time when terminals are made commercially available on the market place. Some features are likely to be rather large and complex, which further increases the risk of interoperability problems unless these features have undergone sufficient interoperability testing (TOT) on real network equipment, and preferably with more than one network in order to improve the confidence of the UE implementation. Thus, avoiding unnecessary UE mandatory features but instead defining a limited set of UE radio classes allows simplification for the interoperability testing.
Given the discussion above, it seems beneficial for the introduction of 3GPP LTE to limit the combination of radio capabilities to a clearly defined subset and ensure that a given set of parameters is supported by certain UE classes as well as networks for rapid 3GPP LTE deployment. It seems unrealistic to mandate only one single UE class which always mandates the maximum capability.
The aim is to ensure on the one hand that high end 3GPP UEs, supporting data rates representing state of the art level and competitive with other radio technologies are defined, while the medium and lower data rates aim to reduce implementation cost for chipset/terminal vendors and allow adoption of most cost efficient solutions for different market segments. It is expected that the support of the high end data rate terminals is ensured from the very beginning.
In 3GPP LTE, introduction of high order modulation, like 256 quadrature amplitude modulation (QAM), may be considered as a part of improvement of spectral efficiency. In this case, a method for configuring UE capabilities supporting higher modulation order may be required.